Electrical circuit breaker with multicurrent rating and improved operating means

ABSTRACT

THIS CIRCUIT BREAKER IS A MOLED CASE, MULTI-POLE CIRCUIT BREAKER OF WHICH EACH POLE HAS ITS INDIVIDUAL TOGGLE MECHANISM FOR CLOSURE AND RELEASE. THESE MECHANISMS ARE OPERABLE BY A COMMON OPERATING HANDLE SO AS TO CAUSE ALL OF THE POLES TO CLOSE SIMULTANEOUSLY. EACH TOGGLE MECHANISM IS SPRING BIASED IN THE OPENING DIRECTION, BUT IS LATCHED IN POLE CLOSING POSITION BY A HIGH MAGNETIC RELEASE WHICH RELEASES INSTANTANEOUSLY IN EVENT OF A HIGH CURRENT SHORT CIRCUIT, BY A LOW MAGNETIC RELEASE WHICH RELEASES AT THE END OF A SLIGHTLY LONGER INTERVAL, SUCH AS IN EVENT OF A TEMPORARY HEAVY OVERLOAD, AND BY A THERMAL RELEASE WHICH RELEASES AT THE END OF A SOMEWHAT LONGER INTERVAL DUE TO THERMAL EFFECTS CREATED BY LONGER SUSTAINED, BUT LESSER, OVERLOADS. THE HIGH MAGNETIC RELEASE OF EACH POLE OPERATES IN BYPASSING RELATION TO PARTS OF THE ASSOCIATED TOGGLE MECHANISM AND TO THE OTHER RELEASES FOR QUICKER RELEASING ACTION. THE LOW MAGNETIC RELEASE IS ADJUSTABLE FOR RELEASING IN RESPONSE TO PRESELECTED FLUX INTENSITIES. TRANSFORMERS SUPPLY SECONDARY CURRENT FOR OPERATING THE THERMAL RELEASES FOR THE POLES, RESPECTIVELY. THE AIR GAPS IN THE MAGNETIC FLUX PATH OF EACH TRANSFORMER CAN BE CHANGED READILY BY REMOVABLE RATING COLUMNS TO ASSURE SUBSTANTIALLY THE SAME SECONDARY CURRENT FOR ANY SELECTED PRIMARY CURRENT WITHIN THE RATED CAPACITY OF THE CIRCUIT BREAKER.   THE TERMINAL STRAP OF EACH POLE ACTS AS THE PRIMARY FOR CREATING THE OPERATING FLUXES. MEANS COMMON TO ALL OF THE POLE MECHANISMS ASSURE CONCURRENT RELEASE OF ALL TOGGLE MECHANISMS INSTANTLY UPON RELEASE OF ANY ONE OF THEM. SPECIFIC SAFELY FEATURES ARE ALSO PRESENT.

I Feb. 2, 1971 CHABQT 7 3,560,899

ELECTRICAL CIRCUIT BREAKER WITH MULTI-CURRENT RATING AND IMPROVED OPERATING MEANS Filed Nov. 18, 1968 7 Sheets-Sheet 1 1 4 OH 0 o )1 o H INVENTOR. 5 W 6- fly/A /:ATTOENEY,

Feb. 2, 1971 F. E. CHABOT ELECTRICAL CIRCUIT BREAKER WITH MULTI-CURRENT RATING AND IMPROVED OPERATING MEANS 7 Sheets -Sheet 3 Filed Nov. 18, 1968 INVENTOR. 5] 4" Q Llw flf Feb. 2, 1971 F E CHABQT 3,560,899

ELECTRICAL CIRCUIT BRE AKER WITH MULTI-CURRENT RATING AND IMPROVED OPERATING MEANS Filed Nov. 18, 1968 7 Sheets-Sheet 4 INVENTOR. M I I5 95 92 BY 4 E I I ATTORNE Y.

3,560,899 CURRENT RATING AND Feb. 2, 1971 F. E. CHABOT ELECTRICAL CIRCUIT BREAKER WITH MULTI IMPROVED OPERATING MEANS 7 Sheets-Sheet 5 Filed Nov, 18, 1968 INVENTOR. Jaw a. M

MM? 7 ATTORNEY.

Feb. 2, 1971 F CHABQT 3,560,899

- I ELECTRICAL CIRCUIT BREAKER WITH MULTI-CURRENT RATING AND IMPROVED OPERATING MEANS 7 Sheets-Sheet 6 Filed Nov'. 18, 1968 v I INVENTOR.

Feb. 2, 1971 F. E. ELECTRICAL CIRCUIT BREAKER Filed Nov. 18, 1968 CHABOT WITH MULTI-CURRENT RATING AND IMPROVED OPERATING MEANS 7 Sheets-Sheet A ATTORNEY.

United States Patent US. Cl. 335-35 Claims ABSTRACT OF THE DISCLOSURE This circuit breaker is a molded case, multi-pole circuit breaker of which each pole has its individual toggle mechanism for closure and release. These mechanisms are operable by a common operating handle so as to cause all of the poles to close simultaneously. Each toggle mechanism is spring biased in the opening direction, but is latched in pole closing position by a high magnetic release which releases instantaneously in event of a high current short circuit, by a low magnetic release which releases at the end of a slightly longer interval, such as in event of a temporary heavy overload, and by a thermal release which releases at the end of a somewhat longer interval due to thermal effects created by longer sustained, but lesser, overloads.

The high magnetic release of each pole operates in bypassing relation to parts of the associated toggle mechanism and to the other releases for quicker releasing action.

The low magnetic release is adjustable for releasing in response to preselected flux intensities.

Transformers supply secondary current for operating the thermal releases for the poles, respectively. The air gaps in the magnetic flux path of each transformer can be changed readily by removable rating columns to assure substantially the same secondary current for any selected primary current within the rated capacity of the circuit breaker.

The terminal strap of each pole acts as the primary for creating the operating fluxes.

Means common to all of the pole mechanisms assure concurrent release of all toggle mechanisms instantly upon release of any one of them.

Specific safety features are also present.

The circuit breaker of the present invention is a molded case circuit breaker having a plurality of poles. Each pole includes one terminal strap with stationary contacts thereon and another terminal strap connected by flexible conductors to movable contacts which are mounted on a movable contact carrier. A toggle closure and release mech anism is provided for each pole and is operable for driving the associated movable contact carrier into contact making position and for releasing the carrier. Each toggle mechanism returns its associated pole to open position upon the occurrence of certain preselected conditions.

Novel features of the invention reside in the latches of each toggle mechanism. One latch is a high magnetic release latch which releases upon the occurrence of high current short circuits. A second latch is a low magnetic release latch which releases due to a low magnetic field resulting from a temporary overload. A third latch is a thermal release latch which releases due to the heating of a bi-metal strip by secondary current from a transformer. The high magnetic release latch is arranged so that the other latches are by-passed, whereby operation of less than all of the latches releases the toggle mechanism so that it returns the carrier to open position in a 3,560,899 Patented Feb. 2, 1971 much shorter instant of time than would be required were it necessary for all of the parts to operate in succession for tripping.

The flux for operation of the high magnetic release latch and the low magnetic release latch, and for energizing the transformer to provide current for the thermal release latch, is obtained by employing the terminal strap as a single turn primary for the associated pole.

Trip rating columns with diflerent magnetic paths therethrough are provided in the magnetic path of the transformer and are arranged so that they can be removed and replaced for preselecting the magnetic path of the transformer in relation to difierent selected primary current demands to be imposed on the pole, within the rating thereof. This makes it possible, without changes in the toggle mechanisms, to obtain the same secondary current for different selected primary currents.

The toggle mechanisms of all poles are connected together by a rigid insulating tie bar operated by an external operating handle. Each toggle mechanism has a movable contact carrier which, during operation of the mechanism to move the carrier into final closing position, is biased resiliently toward contact opening position by its mechanism. Since slight variations in toggle actions and movements of parts of the dififerent toggle mechanisms might cause the carriers to close other than simultaneously, a common latch for the carriers and a release device therefor is provided. The common latch engages the carriers of all poles and constrains them from continued movement toward final closing position until the one most delayed in travel toward closing position has reached a latched position, and then unlatches all of the carriers simultaneously for movement to final closed position. This assures that all poles close simultaneously regardless of the minor time variation inherent in their toggle link operations.

A common trip shaft is provided and interconnects all of the toggle closure and release mechanisms so that tripping of any one toggle mechanism results in instant tripping of the others.

Provision is made for adjustment of the low magnetic release of each mechanism so that it will release under ditferent selected load conditions.

A trip lever is provided for each pole and is arranged to mechanically trip the low magnetic mechanism of that pole in event its trip rating column is removed while the pole is closed, and so as to prevent latching of the toggle mechanism of the associated pole in closed position if its rating column is not in place.

The case cover has a portion which can be removed for installing and removing the rating columns without exposing the other mechanisms within thecase.

Another trip lever is also provided and arranged for access from the exterior of the case for manual tripping of all toggle mechanisms while the cover of the circuit breaker case is closed.

Various specific objects and advantages will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a top plan view of a circuit breaker embodying the principles of the present invention, part of the cover being broken away for clearness in illustration;

FIG. 1A is a fragmentary sectional view, taken on line 1A 1A of FIG. 1, and showing a manual trip mechanism for the circuit breaker;

FIG. 2 is an enlarged vertical sectional view taken on the line 22 of FIG. 1, showing the poles in closed position, part thereof being shown in elevation for clearness in illustration and a portion of the cover and casing wall being removed for showing the handle linkage;

FIG. 3 is an enlarged vertical sectional view taken on the line 33 in FIG. 2, part thereof being shown in elevation;

FIG. 4 is an enlarged fragmentary top plan view of the circuit breaker, showing part of its enclosing case and one of the toggle closure and release mechanisms, with the operating parts in the pole closing position;

FIG. 5 is a top plan view of one of the toggle closure and release mechanisms showing the mechanism when the associated pole is in Open position;

FIG. 6 is a right side elevation of the structure illustrated in FIG. 5, as viewed generally along the line 66 thereof;

FIG. 7 is a fragmentary front elevation of the structure illustrated in FIGS. 5 and 6, some parts being omitted for clearness in illustration;

FIG. 8 is a fragmentary top plan view of one of the toggle mechanisms and its contacts, parts thereof being omitted for showing more clearly the high magnetic re-- lease latch, the low magnetic release latch, and thermal release latch, of the toggle mechanism;

FIG. 9 is a right side elevation of the structure of FIG.

FIG. 10 is a front elevation of the structure shown in FIGS. 8 and 9; and

FIGS. 11 and 12 are front and right side elevations, respectively, each partly in section, of a rating column used in the present invention.

Referring to the drawings, the circuit breaker is enclosed in a molded casing 1 having side Walls 2, a fron wall 3, a rear Wall 4, and a bottom wall 5. The casing 1 is divided into compartments by partition walls 6 so as to isolate each unit electically from the others, and suitable insulating barriers are interposed between the parts where required. The casing is closed at the top by a removable cover 7, as best illustrated in FIG. 2. At one end the cover 7 has a supplemental cover 8 with windows 9 therein for exposing indicia on rating columns, later to be described, within the casing 1. The cover 7 is provided with an opening '10 surrounded by an upstanding annular boss 11 through which a driving connection is made with a common external operating handle 12 which is operable for closing all poles of the circuit breaker.

Since the poles are identical, only one pole and its individual closure and release toggle mechanism is described herein in detail.

Each pole includes terminal straps 15 and 16, respectively, which are mounted on the bottom wall 5 of the casing 1, and extend out of the front and rear of the easing, respectively.

As best illustrated in FIGS. 2, 8 and 9, a plurality of movable contact blades 17 are connected to the strap 15, four being shown for purposes of illustration. Each blade -17 carries a contact 18 at one end and at the other end is connected to the strap 15 by a flexible conductor 19. The outer blades 17 are biased toward closed position by springs 20. The inner blades 17 are biased toward a closed position by leaf springs 21 which are connected at one end to the terminal stra 15.

Between the inner blades 17 is a main arc blade 22 which is connected at its inner end to the strap 15 by a flexible conductor 23. At its outer end it carries a contact 24 cooperable with an arc runner 25 on the terminal strap 16. The are blade 22 is driven in the same direction as the blades 17 by the blade carrier, to be described, and carries at its inner end a bracket 26 having lateral arms 26a engaging the upper faces of the leaf springs 21. The springs are arranged to be engaged and stressed by the movable blade carrier for yieldably urging the outer blades 17 to closed position as the carrier is moving toward closed position and the leaf springs 21 are arranged to be engaged and stressed b the arms 26a as the arc blade 22 is moved toward closed position by the blade carrier.

Referring to the movable blade carrier of the pole and the closure and release toggle mechanism therefor, each toggle mechanism includes a frame 29 comprised of frame members 30 spaced laterally of the casing 1 from each other and fixedly secured to the bottom wall 5 in spaced face to face relation by bolts 31. A movable blade carrier 32 is mounted between the frame members 30 for rocking about a horizontal pivot 33 secured fixedly at its ends to members 30, respectively. The blades 17 and 22 are connected to the carrier 32 for lost motion movement relative thereto in the closing and opening direction by bolts 34. The bolts 34 are adjusted so that, in the normal operation of the carrier 32 as it approaches contact making position, the springs 20 and 21 are stressed so as to urge the blades 17 away from the carrier 32 toward closed position to an extent determined by the engagement of the heads of the bolts 34 with the upper face of the carrier 32.

Pivotally mounted on the frame 30 by means of a pivot 35, extending parallel to the pivot 33, is a rockable operating arm 36. The arm 36 comprises a pair of spaced side members 36a connected together by a rigid handle arm 36b for rocking as a unit. Mounted on, and between, the members 36a is a reset roller 37 which is rotatable about a pivot 38 parallel to the pivot 33 and which is used to operate a toggle for closing the contacts.

The toggle mechanism comprises a cradle 40 composed of a pair of laterally spaced cradle members 40a which are mounted for rocking as a unit above a fixed pivot or shaft 41 which is connected at its end to the frame members 30. Each member 40a has a cam surface 42 which is positioned to be engaged and moved by the reset roller 37 when the handle arm 36 is moved in a counterclockwise direction in FIG. 6. When so moved, the arm 36 rocks the cradle 40 about the axis of the pivot 41 in a counterclockwise direction in FIGS. 2 and 6. The cradle members 40a, on a portion spaced beyond the cam surfaces 42 in a direction away from the pivot 41, carry a common biasing roller 43 which is arranged to operate a cradle latching mechanism, later to be described.

Pivotally mounted on the cradle 40 for rocking about coaxial toggle pins 45 are parallel aligned links 46. Each link 46 is pivoted at its lower end to a companion link 47 by means of a pivot pin 48. The lower end of each companion link 47 is connected by a pivot 49 to the movable contact carrier 32.

Springs 50 are connected at their upper ends, by a pin '51, to the arm 36 and are connected at their lower ends to the pivot pin 48.

The springs 50 continually urge the pin 48 upwardly and thereby, through the medium of the link 46, bias the cradle 40 to rotate in a clockwise direction. I

A cradle latch 55 is mounted on the frame for rocking about a fixed pivot 56 which is parallel to the pivot 35 and is connected to the frame 30 and accommodated in parallel slots 57 in the cradle latch 55. The latch 55 is biased in a clockwise direction by means of springs 58 which are connected at their lower ends to rod 59 on the latch 55 and are connected at their upper ends to pins 60. The springs 58 bias the cradle latch 55 clockwise and yieldably hold it against a suitable stop 61, mounted on the frame 30, so as to limit the rocking movement of the latch 55 in the clockwise direction. The cradle latch 55 is so positioned that upon swinging of the cradle member 40 counterclockwise, the roller 43 thereof engages a cam surface 62 on the latch 55 and earns the latch 55 in a counterclockwise direction and then passes beneath a latching shoulder 63 on the latch 55.

In order to latch the cradle latch 55 against counter-' is urged by the roller 65 to rotate counterclockwise about the axis of the pivot 68, when the roller 43 is latched by the latch 55.

From the foregoing description, assuming that the contacts are in open position and the toggle mechanism is tripped, as illustrated in FIG. 6, it can be seen that upon swinging the arm 36 counterclockwise, the roller 37 swings the cradle 40 counterclockwise toward latching position. During this movement the springs 50 pass deadcenter and are urging the toggle links 46 and 47 to collapsed condition. Continued swing of the arm 36 counterclockwise, causes the link 46 to lower, thus forcing the pin 48 to swing counterclockwise about the axis of the pin 49, thus greatly increasing the tension of the springs 50. Therefore, when the cradle 40 is in latched position, the springs 50 are urging the links 46 and 47 toward collapsed position. After the toggle mechanism is set and latched, upon swinging of the arm 36 clockwise, the springs 50 pass dead-center with respect to the toggle pins 45 so that the springs swing the pin 48 clockwise, thus straightening out the toggle links 46 and 47, and thereby depressing the carrier 32 for closing the contacts.

By this same action, the line of force of the springs 50 is brought to the right of the pivot 35 of the arm 36 and thus the springs '50 hold the arm 36 in the On position of the contacts. It will be seen that when in this position, should the cradle 40 be released, the springs 50, acting through the medium of the link 46 and pin 48, will swing the cradle 40 clockwise and pull upwardly on the link 47, thereby moving the carrier 32 to contact opening position with a snap action.

As mentioned, it is desirable that the cradle 40 be unlatched, while the arm 36 is in the On position, upon the happening of any one of a number of different occurrences. The various latching means which are releasable upon the happening of these occurrences, respectively, will now be described.

Pivotally mounted on the pivot 68 for rocking relative to the quick trip latch 66 is a thermal latch lever 70 in the form of two spaced arms 70a secured in fixed position relative to each other. The quick trip latch 66 carries a pin 71 which can engage the underside of the thermal latch lever 70. A biasing spring '72 is connected to the quick trip latch 66 and lever 70 and urges the quick trip latch to rotate clockwise about the pivot 68 relative to the thermal latch lever 70, thus normally holding the pin 71 in yield able engagement with the underside of the lever 70. Consequently, the quick trip latch 66 and lever 70 normally can rotate as a unit, if the lever 70 is unrestrained. The latch 66 can be rotated counterclockwise relative to the lever 70 by force sufiicient to flex the biasing spring 72 while the lever 70 is latched against counterclockwise rotation about the pivot 68, as more fully described hereinafter.

The lever 70 is normally latched against counterclockwise rotation by a thermal trip lever 74 which is pivotally mounted on a pivot 75 on the stationary support members 67. The lever 74 is biased in a clockwise direction by means of a spring 76 and carries a pin 77 which, in the normal position of the lever 74, is disposed beneath the thermal latch member 70 so as to prevent its counterclockwise rotation. The thermal trip lever 74 can be tripped due to thermal eflects and due to low magnetic effects caused by temporary overloads. When tripped due to either of these effects, it releases the thermal latchlever 70 and thereby the quick trip latch 66. A spring 70' is provided to return the lever 70 clockwise.

Referring first to the thermal release, the thermal release lever 74 is provided and arranged to be tripped by moving it in a counterlockwise direction by means of a thermal yoke 80. The yoke 80 has an adjustment screw 81 arranged so that upon flexure of the yoke 80, due to heating to predetermined temperatures, the screw 81 engages the lever 74 and moves it counterclockwise sufficiently to remove the pin 77 from beneath the thermal 6 latch lever 70. This movement releases the lever 70 whereupon the quick trip latch 66 releases the cradle latch 55, so that the contacts are opened by the force of the springs 50.

In order to provide the heating effects to which the bi-metallic yoke 80 is responsive, a magnetic core 82 is mounted so that it passes around the terminal strap 15 which thereby acts as a primary for inducing flux into the core 82. A secondary coil 83 is wound about the core 82 and has terminals 84 connected to opposite arms of the bi-metallic yoke 80. As a result, the current induced in the coil 83 passes through the bi-metallic yoke and, due to the resistance of the latter, causes heating effects therein in a predetermined proportion to the flux induced in the core 82 which, in turn, is dependent upon the current flowing in the terminal strap 15.

As mentioned, the same lever 74 is to be tripped, in event of temporary overloads much below short circuiting loads, by means of a low magnetic release. For this purpose, poles 85, as best illustrated in FIGS. 3 and 10, are connected to the core 82 and terminate in spaced relation to each other to provide a leakage flux gap 86. A low magnetic trip lever 87 is pivotally mounted on the pivot for rocking relative to the lever 74. The lever 87 is in the form of spaced arms 87a connected together by a tie rod 88. This rod 88 is positioned to engage the lever 74 and rock it counterclockwise, thus tripping the thermal latch lever 70, upon rocking of the lever 87 counterclockwise. Return or clockwise movement of the lever 74 is arrested by engagement of an intermediate transverse portion of a spring 89 having its two ends held by a pin 89a on the lever 87, and the transverse portion received in a slot in the lever 74.

In order to rock the lever 87 counterclockwise in response to the flux across the gap 86, the lever 87 carries an armature 90 in attractive relation to the poles 85 and so positioned that, upon predetermined flux intensity across the poles 85, the armature is attracted downwardly and swings the lever 87 counterclockwise for tripping the lever 74. The lever 87 is provided with an arm 87b to which is connected a spring 91 for biasing the lever 87 in the clockwise direction. The spring 91 is connected at one end to the arm 8711. A hook rocker 92 is provided and has arms 92a and 92b. It carries a pivot pin 93 which is slidable vertically in a slot 94 in the casing.

The arm 92a is connected by a pivot 96 to a common adjusting bar 97 which is mounted in the casing for movement endwise and which, upon endwise movement, rocks the rocker 92 about the axis of its pivot 93. The arm 92b is connected to the other end of the spring 91 for increasing and decreasing the tension on the spring 91, depending upon the direction and degree of rocking of the rocker 92.

Since all of the poles of the circuit breaker are to be adjusted for low magnetic release concurrently, a common operating handle 98 is pivotally mounted on a plate 99 in the casing for swinging about a pivot 100. The bar 97 carries a roller 101 which operates in a slot 102 in the operating handle 98 for moving the bar 97 endwise upon rocking of the handle 98. The handle 98 carries at its outer end a knob 103 which is accessible from the exterior of the casing for adjusting tension on the springs 91, thereby determining the degree of overload at which the low magnetic trip lever 87 releases the lever 70 and the quick release mechanism.

Thus in event of long sustained moderate overloads and consequent overheating, the bimetal yoke operates to trip the thermal trip lever 74 so as to release the thermal latch lever 70, thereby causing the contact opening toggle mechanism to open the circuit breaker contacts. On the other hand, for a greater, but temporary, overload the low magnetic release lever is operated to operate the thermal lever 74 and thereby release the thermal lever 70 permitting the contact opening mechanism to trip and open the contacts.

A high magnetic release is also provided and is arranged to operate in case of high short circuit currents in the load circuit even while the thermal trip lever 74 and thermal latch lever 70 remain in latching position. Since such short circuit currents are the most dangerous, it is desirable that the high magnetic release operated thereby operate in as short an instant as possible. Therefore, it is arranged so that it by-passes the levers 70 and 74 and directly releases the quick trip latch 66.

Since the necessity for removing play and for moving several parts to release the mechanism is thereby eliminated, the instant of time required between a short circuit and the release of the contact closing mechanism for opening the contacts is shortened. This high magnetic release comprises a magnetic yoke 104 which passes around the load bar so that the load bar acts as a primary for creating flux in the yoke 104. An armature 105 is in attractive relation to the yoke and is connected by a rod 106 to a connecting plate 107 which is mounted between, and is connected to, the arms 66a of the quick trip latch 66. The parts are positioned so that when adequate flux is provided by the yoke 104 to drive the arature 105, the armature swings the quick trip latch 66 downwardly about the pivot 68 against the bias of the spring 72 relative to the thermal latch lever 70, which remains latched in position by the thermal trip lever 74.

Upon release of the quick trip latch 66, it operates to release the roller 65, thereby releasing the cradle latch 55 from the biasing roller 43. This, in turn, releases the cradle 40 and allows the springs 50, through the medium of the link 47, to move the carrier 32 to open position.

In order to assure the proper flux for the thermal release and low magnetic release, regardless of the amperage selected for the breaker, rating columns 110 are provided, one for each unit. As best illustrated in FIGS. 3, 11, and 12, each rating column comprises a body of insulating material in which are embedded a plurality of magnetic core strips 111. These strips are arranged so that when the column is in operating position in the circuit breaker case or enclosure, the strips, by their spacing, provide a flux path determining the intensity of flux in the magnetic path of the low magnetic release latch and through the coil 85 of the thermal release latch for a given load bar current. Thus, for a rated high or low total amperage through the terminal strap 15, the same intensity of flux can be provided for the low magnetic release rating columns 110. This can be done without removing the cover 7, as is later described. The same applies to the flux supplied through the secondary coil 83.

In general, it is desirable that the contacts of all poles be closed simultaneously and, for this purpose, a common closure release bar 114 is provided. This bar is connected to a plurality of pairs of hook arms 115, rockably mounted on the pivots or shaft 41 of the cradle 40 and one adjacent each frame member 30 of the associated carrier 32. Springs 116 bias the bar and arms 115 counterclockwise. Each arm has a latching shoulder 117. In normal position of the bar 114, the hook arms 115 are rocked so that their latching shoulders 117 engage latch pins 118 which are provided on the carrier 32. Thus, as the handle 36 is swung clockwise for closing the contacts, it can drive the carriers 32 against the biasing force of the springs 50 on the links 46-47, toward closed position until all the pins 118 strike the shoulders 117 and the cloususe of the contacts is prevented. The yieldable force of the springs 50 of each carrier permits its temporary latching by the shoulders 117 While permitting continued movement of the arm 36.

The bar 114 is provided with a lever 120 carrying an adjustable abutment screw 121 which, when engaged by the common operator, is forced in a direction to rock the bar 114 clockwise and release the shoulders 117, thus allowing the carriers to be moved against the springs 50 so as to close all of the contacts of all poles simultaneously. This arrangement is provided so all of the poles can close simultaneously.

For this same purpose, all of the arms 36 are fixedly connected to a common cross bar 122 so that all of the arms 36 can be moved concurrently by the exterior operating handle of the circuit breaker. Thus, as the arms 36 approach closely to closing position, the screw 121 is engaged by the cross bar 122 and rocks the bar 114 so as to release all of the shoulders simultaneously.

It is also desirable that if any one of the pole operating mechanisms is tripped, the other mechanisms are tripped substantially simultaneously therewith. For this purpose, a common trip shaft 125 is mounted in the case for rocking about an axis extending parallel to the rocking axes heretofore described. The shaft 125 carries a plurality of trip arms 126 arranged one for each of the poles. Each arm 126 has one end 126a positioned to be engaged by the biasing roller 43 of the associated cradle 40 when the cradle rocks clockwise upon release. The other end 126 b is positioned to strike and trip the associated thermal trip lever 74 When the shaft 125 is rocked counterclockwise by the roller 43. The shaft 125 is biased clockwise by a spring .127. Thus upon tripping of any one of the mechanisms for opening, the shaft 125 is rocked so that the arms 1261: trip the thermal trip levers of the other mechanisms with which they are associated, respectively.

For safety it is desirable to trip the toggle closing and release mechanism of each pole in event it is closed and a rating column 110 is removed and to prevent latching of the toggle in closed position until a rating column is inserted. For this purpose, as best illustrated in FIG. 10, a release lever 130 is mounted in the case adjacent each mechanism for rocking about a pivot 131. The lever 130 is biased by a spring 132 in a direction for engaging and moving the armature of the low magnetic release in a direction for tripping the mechanism. The strength of spring 132 is such that it can trip the low magnetic release when the lever 130 is free to be rocked by the spring 132 about its pivot .131. The lever 130 has an arm 133 which is positioned so as to be engaged by a lug 134 on the lower end of the rating column 110, as the rating column is being installed and moved to final position, and thereby rocked downwardly so as to rock the lever 130 upwardly and against the force of the spring 132 so that the lever 130 cannot drive the low magnetic release armature 90 to tripping position. Thus, it is seen that if the rating column is removed, the lever swings counterclockwise and trips the low magnetic release. On the other hand, the contacts cannot be latched in closed position so long as the lever 130 is held in the releasing position by the spring 132, and hence a rating column must be in place before the units can be latched in contact making position.

It is desirable that the rating columns 110 be removable from the case without exposing the rest of the mechanism and for this purpose the supplemental cover 8 is provided and is detachably secured to the cover 7 by screws so as to be removable without removing the cover 7. The Windows 9 are positioned so that the indicia on the upper ends of the rating columns can be read while the supplemental cover 7 is in place.

In order to trip all of the mechanisms While the cover 7 is in place, a slide member 135 is mounted in the casing and is biased to an extended position by the spring 127 on the shaft 125, through the medium of a pin 136 on the shaft. The cover has an opening through which the slide member 135 is accessible for manual depression. This slide member 135 carries a finger 137 which, upon depression of the slide member 135, engages the pin 136 on the common trip shaft 125 and rocks the shaft in a direction to trip all of the mechanisms simultaneously. For closing all of the units simultaneously, the common tie bar 122 is provided with a suitable bracket 138, having at the upper end a ball 139 by which it is connected to an extensible connector 140. The connector .140 is pivotally connected at the opposite end by a pivot 141 to a rock lever 142 which is mounted for rocking about a pivot 143 supported in one of the partition walls 6 of the case. The end of the position by the force of the springs 50 until one of the latches is tripped. Upon unlatching for any cause, the same springs 50 open the contacts.

device is provided which is operative upon removal of a rating column when the toggle mechanism is in the set position, to trip the latch means, and which is operative to prevent setting of the latch means in latching position relative to toggle mechanism in the absence of a rating column in said predetermined position with respect to the 55 core.

lever 142 opposite from the pivot 141 is connected by a pivot 144a to a rock arm 144 which is rotatable with the operating handle 12 so that upon swinging the handle 12 in the direction for closing the contacts, all of the units are moved to closed position concurrently, as hereinbefore described.

Accordingly, to set the circuit breaker in closed position, the arm 36 is first swung counterclockwise to latch the toggle with the springs 50 in stressed condition, and then clockwise until the direction of force of the springs 50 is past dead-center in a clockwise direction beyond the pivot 35. This movement expands the toggle and thereby urges the pin 118 on the carrier 32 firmly against the latch shoulders 117. Continued clockwise movement causes the common bar 122 to engage the screw 121 and release the hook arm 115 whereupon the contacts of all of the poles are moved concurrently to closed position with a snap action.

The arm 36 and contacts of each pole are held in closed Having thus described my invention, I claim:

1. A circuit breaker comprising:

a settable contact operating toggle mechanism;

latch means for latching the toggle mechanism in its set position;

magnetic means in inductive relation to a current path through the circuit breaker for releasing the latch means and having a flux path including a core;

a plurality of flux conducting rating columns each of which is operative when placed in a predetermined position relative to the core to provide a portion of said flux path;

each column having a fiux conductivity different from that of each of the others whereby the conduction oi flux through the path is different for each column placed in a predetermined position with respect to the core;

means for detachably mounting each of the columns, se-

lectively, in said predetermined position with respect to the core for thereby changing the reluctance of the total flux path in accordance with the selected column; whereby the magnetic means may be made responsive to the same intensity of magnetic flux for different rated currents, so that the circuit breaker rating can be changed while using the same magnetic means.

2. The structure according to claim 1 wherein a trip 3. A multi-pole circuit breaker comprising:

a plurality of contact carriers each movable to closed contact and open contact positions, respectively;

settable toggle mechanisms for the carriers, respectively, each settable toggle mechanism normally being operable when moved to a set position to then move its associated carrier under yielding pressure to closed contact position and being operable upon return from the set position to move its associated carrier to open contact position;

an operator for the toggle mechanisms;

biasing means biasing the mechanisms, respectively, each in a direction for moving its associated carrier to open contact position;

a common closure member connecting the operator to all of the toggle mechanisms for moving the mechanisms substantially concurrently in the setting direction to said set positions, respectively, and then for movement of the member in the opposite direction 75 10 to a predetermined position along a predetermined path;

restraining means for the carriers, respectively, each restraining means normally being positioned to engage its associated carrier as its carrier closely approaches closed contact position and latch its associated carrier against movement to final position by said yielding pressure;

a common release device connected to all of said re straining means and operable when driven to a releasing position to release all of said restraining means concurrently, and

means drivingly connecting the common closure memher to said release device for driving the release device to said releasing position upon movement of the common closure member in said direction beyond said predetermined position.

4. A multi-pole circuit breaker according to claim 3 and further characterized in that each pole comprises:

a terminal strap;

a high magnetic release latch;

a low magnetic release latch;

a thermal release latch;

each of said latches being operative in a first position to latch the toggle mechanism in said set position, and being operative in a second position to release the toggle mechanism for operation by the biasing means for opening the contacts;

a first core in inductive relation to the terminal strap for producing a high magnetic field having a flux intensity in preselected relation to the current flowing through the strap;

a high magnetic armature in attractive relation to the high magnetic field and connected to the high magnetic release latch for releasing it upon the occurrence of short circuit currents in said strap;

a second core in inductive relation to the strap for producing a low magnetic field having a flux intensity in preselected relation to the current flowing through the strap;

pole pieces connected to the second core so as to bypass part of the flux induced therein so as to establish a low magnetic field;

a low magnetic armature in attractive relation to said low magnetic field and connected to the low magnetic release latch for releasing it upon the flow through the strap of current exceeding a predetermined maximum below short circuit currents;

a secondary winding in inductive relation to said second core;

heat responsive means connected to the terminals of the secondary winding and heated by the secondary current, and operative when heated by the current to a predetermined temperature, to release the thermal release latch;

a plurality of flux conducting rating columns each of which is operative when placed in a predetermined position relative to the second core, to change the flux conductivity thereof;

each column having a flux conductivity different from that of each of the others, whereby the conduction of flux through said second core is different for each column placed in a predetermined position with respect to the second core; and

means for detachably mounting each of the columns,

selectively, in said predetermined position with respect to the second core.

5. The structure according to claim 4 wherein resilient biasing means are connected to the low magnetic armature and bias it in a direction opposite to its direction of movement for tripping the low magnetic release latch;

the circuit breaker includes an enclosure;

adjustment means in the enclosure are provided for adjusting the biasing force of the resilient biasing means; and

an operating handle extends out of the enclosure and is connected to the adjustment means for adjusting the biasing means.

6. A circuit breaker comprising:

a stationary contact;

a movable contact carrier;

a complementary movable contact carried by the carrier;

settable toggle mechanism connected to the carrier and operative to move the carrier to contact closing position when the toggle mechanism is moved to a set position and operative upon return from the set position to move the carrier to open contact position;

biasing means connected to the toggle and biasing the toggle mechanism for movement in a direction for moving the carrier to contact opening position;

said toggle mechanism including a rocker mounted for rocking about a predetermined axis;

a toggle link connected at one end to the carrier and at the other end to the rocker in spaced relation to said axis;

an operator drivingly connected to the rocker for rocking it in one direction to set the toggle mechanism in contact closing position;

a latch abutment on the rocker in spaced relation to said rocking axis;

a first latch element movable into latching engagement with the abutment when the rocker is moved to position to set the toggle in contact closing position;

biasing spring means biasing the latch element into said latching engagement;

said biasing means being operative to bias the rocker to rock in a direction opposite from said one direction with force to overcome said biasing spring means and move the first latch element out of engagement with the abutment;

a high magnetic release latch movable to a latching position with respect to the first latch element and operative in said position to hold the first latch element in latching position;

means biasing the high magnetic release latch to latching position;

a supplemental latch element operative to be latched in latching position and when in latching position to hold the high magnetic release latch in latching position under predetermined yielding pressure, and operative when released to become movable as a unit with the high magnetic release latch;

a latch lever engageable with the supplemental latch element for latching the supplemental latch element in latching position and disengageable from the supplemental latch element for releasing the supplemental latch element;

magnetic release means operable in respons to short circuit current conducted through the circuit breaker to move the high magnetic release latch against the force of said predetermined yielding pressure to release the high magnetic release latch from the first latch element while the supplemental latch element remains in said latching position; and

additional means connected to the supplemental latch element and operative in response to predetermined currents, below short circuit current, flowing through the circuit breaker, to release the supplemental latchelement while the magnetic release means is unenergized by said short circuit current.

7. The structure according to claim 6 wherein the additional means comprises a thermal release means and a low magnetic release means each of which is connected to the supplemental latch element for moving the supplemental latch element to releasing position, and each of which is operative in response to a different predetermined current from the other, and independently of the other, for eifecting its said movement.

8. A circuit breaker comprising:

a stationary contact;

a movable carrier;

a complementary movable contact carried by the movable carrier;

settable toggle mechanism connected to the carrier and operative to move the carrier to closed contact position after the toggle mechanism is moved to a set position, and operative upon return from the set position to move the carrier to open contact position;

biasing means connected to the toggle mechanism and biasing the toggle mechanism for movement in a direction for moving the carrier to open contact position;

a terminal strap for conducting load current when the contacts are closed;

field producing means in inductive relation to the strap for providing a high magnetic field having a flux intensity in preselected relation to short circuit currents flowing through the strap and for providing a low magnetic field of predetermined intensity, less than that produced by said short circuit currents, at predetermined overload currents, below said short circuit currents in said strap;

a high magnetic release latch and a low magnetic release latch, each latch being settable, by setting the toggle mechanism in said set position, to latch the toggle mechanism in its said set position against the force of the biasing means;

a high magnetic release armature arranged in attractive relation to said high magnetic field and rendered operative to trip the high magnetic release latch by flux of the intensity created by short circuit currents in said strap; and

a low magnetic release armature arranged in attractive relation to said low magnetic field and rendered operative to trip the low magnetic release latch when the low magnetic field reaches its said predetermined intensity.

9. The structure according to claim 8 wherein a thermal release means is provided and includes a thermally responsive means which is operative when heated to a predetermined degree to trip the toggle mechanism; and

said thermal release means includes a secondary winding in inductive relation to, and operative when energized by, predetermined flux created by long sustained currents in the strap, less than said predetermined overload currents, to heat said thermally responsive means to said predetermined degree.

10. The structure according to claim 9 wherein the thermally responsive release means includes a bi-metal strip having a predetermined resistance to the flow of current therethrough, the secondary winding has terminals which are connected to said strip at spaced locations along its length, respectively; and

the secondary winding and portion of the strip between said spaced locations form a closed loop secondary circuit.

11. The structure according to claim 9 wherein the field producing means includes a core in inductive relation to the terminal strap for producing flux for said low magnetic field and for energizing said secondary winding; and

pole pieces are connected to said core so as to by-pass around the secondary winding part of the flux induced in the core, whereby the low magnetic field is established by the by-pass part of the flux and the secondary is heated by part only of the induced flux.

12. The structure according to claim 8 wherein said high magnetic release latch is directly connected to the toggle mechanism and is operable by the high magnetic armature to release the toggle mechanism directly while the low magnetic release latch is in latching position;

the low magnetic release latch is connected to the high magnetic release latch so as to hold it in latching 13 position under yielding pressure which can be overcome by the high magnetic armature when the latter is subjected to said flux which is due to said short circuit currents; and said low magnetic release latch is operative to release the high magnetic release latch while the high magnetic armature is subjected to flux caused by currents in the strap less than short circuit currents. 13. The structure according to claim 12 wherein a thermal release latch is provided and is operative, in response to flux produced by currents in said strap, which currents are of longer duration and of less intensity than the currents to which the low magnetic armature is responsive, to release the high mganetic release latch while the high magnetic release armature is subject to flux caused by currents in the strap which are less than short circuit currents; and

the high magnetic release latch is operable while the thermal release latch remains in latching position. 14. The structure according to claim 12 wherein said toggle mechanism includes a set of parts connected for a chain collapse reaction when released, and operative when subject to said chain collapse reaction, to move the carrier to contact open position;

the low magnetic release latch, when released, initiates the chain collapse reaction of the parts of said set beginning with a predetermined part and ending with a final release part; the high magnetic release latch, when released, initiates a chain collapse beginning with an intermediate part between said predetermined part and the final release part and independently of the collapse of parts from said predetermined part to said intermediate part. 15. The structure according to claim 12 wherein said toggle mechanism includes a set of parts connected for a chain collapse reaction when released, and operative,

when subject to said chain collapse reaction, to move the carrier to contact open position;

a thermal release latch is provided and is operative in response to flux produced by currents in said strap, which currents are of longer duration and of less intensity than the currents to which the low magnetic armature is responsive, to release the high magnetic release latch while the high magnetic release'armature is subjected to flux caused by currents in the strap which are less than short circuit currents;

each of that group of latches which group comprises the low magnetic release latch and the thermal release latch, when released, initiates, respectively, a chain collapse reaction of a predetermined number of said parts beginning with an associated part;

the high magnetic release latch, when released, initiates the chain collapse reaction of less parts than said predetermined number, beginning with an inter- References Cited UNITED STATES PATENTS 1,877,698 9/1932 Scott 200l53(.7) 2,939,929 6/l960 Hobson 335-36 3,353,128 11/1967 Gauthier 335-35 3,440,580 4/1969 Molenaar 33535 HAROLD BROOME, Primary Examiner US. Cl. X.R. 

